Establishment of A Standardized Osteotomy Model for Future in Vivo Evaluation of Bone Adhesives

Abstract Bone fractures are frequently occurring injuries, and their treatment often includes metal implants, which may require a second surgery for removal, causing pain and added costs. Bone adhesives have the potential to replace metal implants in the treatment of bone fractures. Advancing bone adhesive research requires a suitable in vivo model. Such a model should provide standardized osteotomy conditions in load-bearing bones, and enable quantitative assessment of multiple healing parameters (e.g., radiographic, biomechanical, histological). This study aimed to develop a standardized osteotomy model for testing bone adhesives. A transverse mid-shaft osteotomy of the right femur was performed in 3-month-old female Sprague-Dawley rats and stabilized with an intramedullary cannula. In vivo micro-computed tomography (micro-CT) scans were acquired weekly to monitor bone healing. After 12 weeks, the bones were analyzed biomechanically, histologically, and by ex vivo micro-CT. In vivo CT analysis demonstrated a progressive increase in bone volume, indicating ongoing healing. Histological staining revealed endochondral ossification, and bony bridging scores supported these findings. Biomechanical testing showed reduced bone strength compared to intact femora. These results suggest moderate stabilization with an intramedullary cannula, which provides borderline stability, making it a promising setup for assessing whether additional stabilization by bone adhesives could improve outcomes. In conclusion, we established a simple and reproducible rat model. Future studies may use this model to evaluate bone adhesives and to investigate their influence on fracture healing metabolism.